PEX Series – Liquefied Gas Pump
The PEX Series ProTech Pumps are unique in the ProTech Air Driven Pump range as they use pistons rather than plungers in the liquid ends. They are correctly described as Double Acting Air Drive with direct coupled Single Ended Double Acting fluid pumps. In this regard, they are very similar to the Haskel Models ATV-4 & ATV- 8 and DTV-4 & DTV- 8. The use of the piston in the liquid end allows for high pressure fluid outlet flow in both directions of the reciprocating pump action thus making the pump double acting and highly efficient. All ProTech PEX Series Pumps use our 160mm diameter air drive reciprocating motor with an 80mm stroke thus achieving much higher flow rates than the Haskel ATV range. The PEX Series pumps are suitable for liquids, gases and vapours – making them the perfect as a liquefied gas pump. The PEX series uses PTFE and Viton seals so has excellent fluid compatibility.
How the PEX Series Pumps Work
To obtain this double acting pump effect in the ProTech PEX Series and the Haskel ATV/DTV Series, a single piston pump is mechanically connected to one end of the air drive motor by way of an interconnecting piston rod. The volume taken up by the piston rod (called the annulus) results in the pump having slightly less pump outflow volume on one stroke than the reciprocating stroke. It also results in the pump having a slightly different stall pressure depending on whether the stall pressure is reached on the “pull” or “push” strokes of the pump. None of this has an adverse effect on the pump’s performance but does give rise to another excellent feature and benefit of this type of pump arrangement.
The PEX series uses “gas-tight” ball checks on the two inlet and outlets which makes them very suitable for pumping gases and vapours as well as liquids. The use of stainless steel and PTFE seals in the wetted areas (liquid pump end) makes them suitable for pumping corrosive fluids including water. By attaching pipework to the bare PEX Pump the two inlets and outlets can be manifolded to become a single port inlet and a single port outlet. Changing the pipework arrangement on the ProTech PEX Series pumps and connecting the outlet of the larger volume section of the pump to the smaller volume inlet, we put the two pumping volumes in series with one another. This, in effect, means the same pump can be used as a 2-stage pump or gas booster.
To achieve this ability to pump gases and vapours Haskel require the use of their more expensive Gas Booster models such as the AGD-4. All PEX Series pumps are suitable for liquids, gases and vapours. They are also capable of drawing a vacuum down to 11.25 psi(absolute) in the 2-stage configuration. Interconnecting pipework can be supplied by ProTech thus becoming packaged systems within themselves. In this guise we refer to these pumps as PEX Extraction Systems.
The PEX Range
There are, currently, two models of PEX pumps both using the familiar ProTech 160mm (6.3″) diameter by 80mm stroke reciprocating air motor. The PEX4-46 has a 4:1 ratio with a 47.55 cubic inch displacement per cycle and a PEX6-25 with a 6:1 ratio and a 28.9 cubic inch displacement per cycle. Both models represent a large improvement in flow rates when compared to the Haskel ATV-4, DTV-4 and EXT-420-2 models which use a 5 1/4” air drive with 2″ stroke.
|Brand||Model||Ratio||Displacement||Separation||Distance Piece||Liquid or Gas|
|ProTech||PEX4-46||4:1||46 cu in||Yes||No||Both|
|ProTech||PEX6-25||6:1||25 cu in||Yes||Yes||Both|
|Haskel||ATV-4||4:1||20 cu in||No||No||Liquid|
|Haskel||DTV-4||4:1||20 cu in||Yes||Yes||Liquid|
|Haskel||AGD-4||4:1||20 cu in||Yes||Yes||Both|
- Transfer at pressure of water, LPG, SF6, Freons and other refrigerant fluids.
- CO2 Fire Extinguisher filling.
- Hydro-static Pressure testing.
- Critical Extraction.
- The extraction of LPG, LNG Freon and Refrigeration Fluids.
- Dust suppression.
This type of air driven pump is used as original equipment on many underground mining machines including models by Ingersoll Rand.
PLEASE NOTE that due to the use of aluminium in the air drive, neither the Haskel ATV nor the ProTech PEX pumps are suitable for underground coal mining applications.
For underground coal mine applications, we manufacture 100% 316 stainless steel pumps under our SiA Pumps brand, for more information please call us on +61 73277 8822.